JP4389354B2 - Hermetic pump device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hermetic pump device that has excellent shut-off from the outside, and is a technique suitable for use in flammable fluids and toxic fluids.
[0002]
[Prior art]
As a hermetic pump device, a bellows pump disclosed in Japanese Patent Laid-Open No. 10-148258 is known. This hermetic pump device uses the inside of a bellows having a hermetic structure as a pump chamber, and performs suction and discharge of a working fluid by utilizing a volume change due to expansion and contraction of the bellows.
[0003]
[Problems to be solved by the invention]
However, the conventional hermetic pump device (bellows pump) has a problem that fatigue is accumulated in the bellows due to internal stress accompanying expansion and contraction. As means for solving this problem, it is necessary to expand and contract in a range where the stress is below the fatigue limit of the bellows. That is, the expansion / contraction amount cannot be increased with respect to the entire length of the bellows, and the physique of the hermetic pump device is increased.
An object of the present invention is to reduce the size of the hermetic pump device by increasing the pump capacity.
[0007]
[Means for Solving the Problems]
[Means of Claim 1 ]
By adopting the means of claim 1 , the working fluid is continuously sucked twice and the working fluid is continuously discharged twice by one expansion and contraction of the bellows. For this reason, the hermetic pump device according to claim 1 has a higher pumping capacity than the conventional one, and the size of the hermetic pump device can be reduced as compared with the conventional one.
[0008]
Specifically, by adopting the means of claim 1 , when the first bellows contracts (the second bellows expands at this time), the pump chamber on the first bellows side in the cylinder defined by the piston is used as the working fluid. And the pump chamber on the second bellows side discharges the working fluid. Subsequently, when the first bellows extends (the second bellows contracts at this time), the pump chamber on the first bellows side in the cylinder defined by the piston discharges the working fluid, and the pump chamber on the second bellows side Performs suction of the working fluid.
That is, the working fluid is continuously sucked twice by the expansion and contraction of the bellows, and the working fluid is continuously discharged twice. For this reason, pump capability is high compared with the past, and the physique of a closed-type pump apparatus can be reduced in size compared with the past.
[0009]
Also, by adopting a means of claim 1, by Rukoto is incompressible fluid sealed in the first bellows and the second bellows, can tell reliably piston volume change in the two bellows, piston The reciprocating drive can be performed efficiently.
[0010]
Further, by adopting the means of claim 1, the space between the piston and the bearing member is covered with a small-diameter bellows, and the shaft member is provided separately from the pump chamber in the cylinder. Even if the incompressible fluid leaks to the pump chamber side in the cylinder, the leaked incompressible fluid is enclosed inside by a small-diameter bellows. For this reason, it is possible to reliably eliminate the problem that the incompressible fluid sealed in the bellows flows into the pump chamber and mixes with the working fluid.
[0011]
[Means of claim 2 ]
By adopting the means of claim 2 , when the shaft member slides on the side different from the pump chamber in the cylinder, the incompressible fluid in the wedge groove is returned into the bellows. For this reason, the incompressible fluid enclosed in the bellows can flow into the pump chamber and be mixed into the working fluid.
[0012]
[Means of claim 3 ]
By adopting the means of claim 3 , since the piston does not slide inside the cylinder, there is no problem that the sliding powder generated by the sliding is mixed into the working fluid.
[0013]
[Means of claim 4 ]
By adopting the means of claim 4 , the pressure between the two pump chambers formed on both sides of the piston in the cylinder is divided by the groove provided on the outer peripheral surface of the piston. A pressure difference can be secured and internal leakage of fluid between the two pump chambers can be suppressed.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described using reference examples, examples , and modifications.
[ First Reference Example ]
FIG. 1 is a cross-sectional view of a hermetic pump device. This hermetic pump device is roughly composed of a pump unit 1 and a drive mechanism 2. Incidentally, pump unit 1 is, for example, those used in the hydrogen supply pump, without passing through the hydrogen, those composed by broken toxicity and durable metallic material (e.g., made of SUS3162 stainless) is there.
[0015]
The pump unit 1 includes a cylindrical cylinder 3, a piston 4 that reciprocates in the cylinder 3, first and second shaft members 5 and 6 provided on both sides of the piston 4, The first and second bearing members 7 and 8 are fixed to the end portions, and the first and second bellows 9 and 10 are fixed to the outer surfaces of the first and second bearing members 7 and 8.
[0016]
The cylinder 3 has a cylindrical shape, and first and second pump chambers 11 and 12 defined by the piston 4 are formed therein. Further, the cylinder 3 is supplied with a suction port 13 for guiding the working fluid to each of the first and second pump chambers 11 and 12, and the working fluid compressed in the first and second pump chambers 11 and 12. 3 is provided with a discharge port 14 for discharging to the outside.
The suction port 13 is provided with a suction valve 15 (corresponding to a valve unit) which is a one-way valve that allows a working fluid to flow only from the fluid inflow unit connected to the suction port 13 into the cylinder 3. The discharge port 14 is also provided with a discharge valve 16 (corresponding to a valve unit) that is a one-way valve that allows the working fluid to flow from the cylinder 3 only to the fluid outflow unit connected to the discharge port 14. The intake valve 15 and the discharge valve 16 are well-known one-way valves such as a reed valve or a check valve.
[0017]
The piston 4 reciprocates inside the cylinder 3 to change the volumes in the first and second pump chambers 11 and 12 defined by the piston 4. The outer diameter of the piston 4 is the same as that of the cylinder 3. It is provided slightly smaller than the inner diameter dimension (for example, about 10 μ to 1000 μ). The piston 4 is supported so as to be capable of reciprocating in the axial direction by sliding of first and second shaft members 5 and 6 provided at both ends. It is provided so as not to slidably contact the peripheral surface. By being provided in this way, there is no problem that the sliding powder generated by sliding is mixed into the working fluid.
[0018]
The first and second shaft members 5 and 6 have a cylindrical bar shape, and are integrated with the piston 4 or fixed to the piston 4 at the center portions on both sides of the piston 4. The outer peripheral surfaces of the first and second shaft members 5 and 6 are supported by the first and second bearing members 7 and 8 so as to be slidable in the axial direction, and the first and second shaft members 5 and 6 are supported. This end face receives a pressure change accompanying a volume change due to expansion and contraction of the first bellows 9 or the second bellows 10.
[0019]
The first bellows 9 has a bellows-like cylindrical shape that elastically expands and contracts in the axial direction, and the piston 4 is driven to reciprocate by utilizing the volume change caused by the expansion and contraction of the first bellows 9. The first bellows 9 has a driving end at the left end in the figure and a fixed end at the right end in the figure.
A disk-shaped first cap 17 is joined to the drive end of the first bellows 9 by a joining technique such as brazing or welding, and the drive end of the first bellows 9 is reciprocated by the reciprocating motion received by the first cap 17. Driven.
The fixed end of the first bellows 9 is joined to the first bearing member 7 by a joining technique such as brazing or welding.
The first working chamber 18 is formed by the space surrounded by the end faces of the first bellows 9, the first cap 17, the first bearing member 7 and the first shaft member 5, and the volume change causes the first shaft member 5 to move. The piston 4 is driven to reciprocate through. A compressive fluid such as an inert gas is sealed in the first working chamber 18 and the second working chamber 20 described later.
[0020]
Similarly to the first bellows 9, the second bellows 10 has a bellows-like cylindrical shape that elastically expands and contracts in the axial direction, and the piston 4 is moved by utilizing the volume change due to the expansion and contraction of the second bellows 10. It is driven reciprocally. The second bellows 10 has a driving end at the right end in the figure and a fixed end at the left end in the figure.
A disk-shaped second cap 19 is joined to the driving end of the second bellows 10 by a joining technique such as brazing or welding, and the driving end of the second bellows 10 is reciprocated by the reciprocating motion received by the second cap 19. Driven.
The fixed end of the second bellows 10 is joined to the second bearing member 8 by a joining technique such as brazing or welding.
The second working chamber 20 is formed by the space surrounded by the end faces of the second bellows 10, the second cap 19, the second bearing member 8, and the second shaft member 6, and the volume change causes the second shaft member 6 to move. The piston 4 is driven to reciprocate through.
[0021]
Here, the first conversion means for converting the volume change due to the expansion and contraction of the first bellows 9 into the drive stroke of the piston 4 by the first bellows 9 including the first cap 17, the first bearing member 7 and the first shaft member 5. The second bellows 10 including the second cap, the second bearing member 8 and the second shaft member 6 are configured to convert a volume change due to expansion and contraction of the second bellows 10 into a driving stroke of the piston 4. Conversion means is configured.
[0022]
The first and second bearing members 7 and 8 are fixed to both ends of the cylinder 3 and partition the inside of the first bellows 9 or the second bellows 10 and the inside of the cylinder 3 as described above. At the same time, the first and second shaft members 5 and 6 are slidably supported in the axial direction.
The first and second bearing members 7 and 8 fill the dead volume generated in the first and second bellows 9 and 10 and improve the compression ratio in the first and second working chambers 18 and 20. The cylindrical boss portion that also serves as a bearing is disposed so as to fill the dead volume.
[0023]
Next, the drive mechanism 2 will be described. Incidentally, the pump unit 1, since by compressing the first bellows 9 elongation second bellows 10, a structure in which the first bellows 9 extends by compressing the second bellows 10 conversely, drive kinematic mechanism 2 The first and second cams 21 and 22 (corresponding to cam means) that alternately press the first and second caps 17 and 19 are used.
[0024]
The drive mechanism 2 is means for expanding and contracting the first and second bellows 9 and 10 and includes an electric motor 23 (external power generation means) for generating a drive force. A first cam 21 that presses the first cap 17 according to the rotation of the output shaft 24 is attached to the tip of the output shaft 24 of the electric motor 23.
A driving pulley 25 is attached to the base portion of the output shaft 24, and the rotation of the output shaft 24 is transmitted to the driven pulley 27 via the timing belt 26. A second cam 22 that presses the second cap 19 according to the rotation of the driven shaft 28 is attached to the tip of the driven shaft 28 that rotates integrally with the driven pulley 27.
Here, the rotation ratio of the drive pulley 25 and the driven pulley 27 is 1: 1, and the first cam 21 and the second cam 22 are provided so as to alternately press the first cap 17 and the second cap 19. .
[0025]
When electrostatic movement motor 23 is activated, first in accordance with the rotation of the output shaft 24 and driven shaft 28, the second cam 21 presses the first cap 17 a second cap 19 alternately. When the first cam 21 presses the first cap 17 and the first bellows 9 contracts, the inside of the first working chamber 18 is compressed, and the piston 4 is driven to the right side in the figure. Then, the volume of the first pump chamber 11 increases, the first pump chamber 11 sucks the working fluid, the volume of the second pump chamber 12 decreases, and the second pump chamber 12 discharges the working fluid. . At this time (when the piston 4 is driven to the right side in the figure), the second shaft member 6 compresses the inside of the second working chamber 20, so that the second bellows 10 extends.
[0026]
Subsequently, when the second cam 22 presses the second cap 19 and the second bellows 10 contracts, the inside of the second working chamber 20 is compressed and the piston 4 is driven to the left side in the figure. Then, the volume of the first pump chamber 11 decreases, the first pump chamber 11 discharges the working fluid, the volume of the second pump chamber 12 expands, and the second pump chamber 12 sucks the working fluid. . At this time (when the piston 4 is driven to the left side in the figure), the first shaft member 5 compresses the inside of the first working chamber 18, so that the first bellows 9 extends.
That is, when the first cap 17 and the second cap 19 are alternately and continuously driven, the first bellows 9 and the second bellows 10 are alternately operated continuously, and the working fluid is alternately supplied from the two suction ports 13. In addition to suction, the working fluid is alternately discharged from the two discharge ports 14.
[0027]
As described above , the hermetic pump device continuously sucks the working fluid twice and discharges the working fluid twice by one expansion and contraction of the bellows. As a result, the pump capacity is higher than that of the conventional bellows type pump, and the size of the hermetic pump device can be reduced as compared with the conventional type.
The hermetic pump device sucks the working fluid that is 180 degrees out of phase and discharges the working fluid that is 180 degrees out of phase by one expansion and contraction of the bellows. And the pulsation of discharge is averaged more than before.
Furthermore, since the hermetic pump device maintains a fine clearance between the cylinder 3 and the piston 4, there is no sliding portion in the first and second pump chambers 11 and 12, and sliding due to sliding occurs. Powder is not generated in the first and second pump chambers 11 and 12. For this reason, there is no problem that the sliding powder is mixed into the working fluid and contaminates the working fluid.
[0028]
[ Second Reference Example ]
As shown in FIG. 2, the pump unit 1 shown in the second reference example fills the first and second working chambers 18 and 20 inside the first and second bellows 9 and 10 with an incompressible fluid such as oil. Is enclosed.
By providing in this way, the volume change in the 1st, 2nd bellows 9 and 10 can be reliably transmitted to the piston 4, and the reciprocating drive of the piston 4 can be performed efficiently.
[0029]
[ Third reference example ]
As shown in FIG. 3, the pump unit 1 shown in the third reference example spreads on the sliding surface of the first and second bearing members 7 and 8 on a different side from the first and second pump chambers 11 and 12. A plurality of wedge grooves 31 having a wedge shape are provided.
By providing in this way, when the first shaft member 5 slides to a different side from the first pump chamber 11, the incompressible fluid that has entered the wedge groove 31 is returned into the first working chamber 18. A problem that an incompressible fluid such as oil flows into the first pump chamber 11 is suppressed.
Similarly, when the second shaft member 6 slides to a different side from the second pump chamber 12, the non-compressed fluid that has entered the wedge groove 31 is returned to the second working chamber 20. A problem that the compressed fluid flows into the second pump chamber 12 is suppressed.
As described above, the provision of the wedge grooves 31 on the sliding surfaces of the first and second bearing members 7 and 8 causes incompressible fluid such as oil to flow into the first and second pump chambers 11 and 12. Therefore, the problem that the incompressible fluid is mixed into the working fluid and contaminates the working fluid is suppressed.
[0030]
[ First embodiment ]
As shown in FIG. 4, the pump unit 1 shown in the first embodiment is covered with a resin-made first small-diameter bellows 32 between the piston 4 and the first bearing member 7 in the first shaft member 5. The shaft member 5 is provided separately from the inside of the first pump chamber 11, and the space between the piston 4 and the second bearing member 8 in the second shaft member 6 is covered with a resin-made second small-diameter bellows 33. In other words, the second shaft member 6 is provided separately from the inside of the second pump chamber 12.
[0031]
By providing in this way, even if the incompressible fluid leaks to the cylinder 3 side from between the first shaft member 5 and the first bearing member 7, the leaked incompressible fluid is internally contained by the first small-diameter bellows 32. Enclosed.
Similarly, even if the non-compressed fluid leaks from between the second shaft member 6 and the second bearing member 8 to the cylinder 3 side, the leaked non-compressed fluid is enclosed inside by the second small-diameter bellows 33. .
As described above, by providing the first and second small-diameter bellows 32 and 33 around the first and second shaft members 5 and 6, the incompressible fluid such as oil can be supplied to the first and second pump chambers 11 and 12. There is no inconvenience of flowing in, and it is possible to reliably eliminate the inconvenience of incompressible fluid mixing into the working fluid and contaminating the working fluid.
[0032]
[ Second Embodiment ]
As shown in FIG. 5, the pump unit 1 shown in the second embodiment is provided with a plurality of grooves 34 along the circumferential direction on the outer peripheral surface of the piston 4.
By providing in this way, the pressure difference between the first pump chamber 11 and the second pump chamber 12 is divided by the plurality of grooves 34, so that the pressure difference between the first and second pump chambers 11 and 12 is divided. Can be secured, and internal leakage of fluid between the first and second pump chambers 11 and 12 can be suppressed. Thus, since the internal leakage of the fluid between the 1st, 2nd pump chambers 11 and 12 is suppressed, pump efficiency can be improved.
[0033]
[Modification]
In the above, an example in which the present invention is applied to a hydrogen supply pump has been shown. It may be applied.
In the above example, the first and second bellows 9 and 10 are driven by the cam. However, the first and second bellows 9 and 10 are driven by converting the rotary motion into a reciprocating motion using a crank or the like. May be provided.
Although the example which used the metal as the material of the pump unit 1 was shown above, you may comprise a part or all of the structural member of the pump unit 1 using resin or rubber | gum. That is, for example, the first and second bellows 9 and 10 may be configured using resin or rubber according to the applied working fluid.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a hermetic pump device ( first reference example ).
FIG. 2 is a sectional view of a pump unit ( second reference example ).
FIG. 3 is a cross-sectional view of a pump unit ( third reference example ).
FIG. 4 is a cross-sectional view of a pump unit ( first embodiment ).
FIG. 5 is a sectional view of a pump unit ( second embodiment ).
[Explanation of symbols]
1 Pump unit 2 Drive mechanism (Means to expand / contract bellows)
3 Cylinder 4 Piston 5 First shaft member 6 Second shaft member 7 First bearing member 8 Second bearing member 9 First bellows 10 Second bellows 11 First pump chamber 12 Second pump chamber 15 Suction valve (valve means)
16 Discharge valve (valve means)
21 First cam (cam means)
22 Second cam (cam means)
23 Electric motor 31 Wedge groove 32 First small-diameter bellows 33 Second small-diameter bellows 34 Groove along the circumferential direction

Claims (4)

The volume change inside the bellows due to expansion and contraction of two bellows arranged opposite to each other is set as a driving stroke of the piston arranged in the cylinder, so that the piston is reciprocated from both sides, In a hermetic pump device that sucks and pumps the working fluid by changing the volume in the cylinder ,
This hermetic pump device
(A) the cylinder having a cylindrical shape;
(B) the piston arranged to reciprocate inside the cylinder;
(C) a first bellows disposed on one end side of the cylinder and having a bellows-like cylindrical shape that elastically expands and contracts in the axial direction;
(D) a second bellows that is disposed on the other end side of the cylinder and has a bellows-like cylindrical shape that elastically expands and contracts in the axial direction;
(E) a shaft member that is provided on both sides of the piston, receives a volume change due to expansion and contraction of the first bellows or the second bellows, and supports the piston in a reciprocating manner in the cylinder;
(F) A bearing member provided at both ends of the cylinder, defining the inside of the first bellows or the second bellows and the inside of the cylinder, and supporting the shaft member slidably in the axial direction;
(G) a suction valve that is provided on both sides of the cylinder and is a one-way valve that guides the working fluid only into the cylinder by a volume change in the cylinder;
(H) a discharge valve that is provided on both sides of the cylinder and is a one-way valve that discharges the working fluid only to the outside of the cylinder by a volume change in the cylinder ;
An incompressible fluid is sealed inside the first bellows and the second bellows ,
The shaft member is provided with a space between the piston and the bearing member covered with a small-diameter bellows so as to be isolated from the pump chamber in the cylinder. The hermetic pump device according to claim 1 ,
A sealed type characterized in that a wedge groove having a wedge shape is provided on a sliding surface of the bearing member on which the shaft member slides in the axial direction and spreads on a side different from the pump chamber in the cylinder. Pump device. In the hermetic pump device according to claim 1 or 2 ,
A hermetic pump device, wherein a fine clearance is formed between the piston and the cylinder. In the hermetic pump device according to any one of claims 1 to 3 ,
A hermetic pump device characterized in that a groove along the circumferential direction is provided on the outer peripheral surface of the piston.

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